this post was submitted on 22 Jun 2023
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Lemmy

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A dev initially suggested in the Lemmy GitHub to remove captchas from future releases altogether because "they're easy to bypass".

Here's the thing though, the lemmy.world instance avoided the daily 10k+ bot signups per day the other instances are currently experiencing simply by activating captchas.

Yes basic OCR easily bypasses them, but the whole point is that you're forcing the spammer to use it, and it costs CPU resources, meaning that for the same budget the spammer will be able to create LESS bot accounts, or none at all if he doesn't know how to automate the use of an OCR. Compare that with the current situation where anyone who followed a Python crash course can easily write a small script doing tens of thousands of automated signups using just the requests module.

Please enable captchas by default in future releases. You can try out other proposed solutions like hashcash too but IMO focus on the low hanging fruit first and make captchas a default in 0.18 already. One barrier, no matter how weak it is, is much better than no barrier at all.

And to those who maintain websites that list instances and rank them by size, you are also contributing to this problem by adding an incentive for bad actors to inflate their own instances. Please either remove that ranking, or remove the spammy looking instances by hand.

Also, maybe change the user count such that only users having clicked on the verification link are counted.

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[–] [email protected] 42 points 1 year ago (2 children)

Completely agree, captcha's aren't gonna make it impossible to make bots, but it makes it more complicated. It will force bad actors to invest more time in it. Wich will turn some part of them away.

On a positive note, I think the fact that we see so many bot signups shows lemmy (the fediverse in general) is growing and matters, otherwise people wouldn't spend so much time and resources to make these bots. All big platforms have these kind of problems and need to learn how to deal with them.

[–] [email protected] 5 points 1 year ago* (last edited 1 year ago)

yeah it was never about making it impossible, only about making it inconvenient enough that it's manageable

[–] [email protected] 17 points 1 year ago (3 children)

I mean, it's a currently approved PR

There's also an active Issue about replacing captchas (which are often an issue privacy-wise) with a mCaptcha, where you computer does "Bitcoin-Like" useless calculations which the server easily can verify that you did.
So it would be much more costly to make a billion spam accounts

[–] [email protected] 3 points 1 year ago

that's awesome but is it a default on new instances?

[–] [email protected] 2 points 1 year ago

This is the right move I think.

[–] [email protected] -2 points 1 year ago

I'm very skeptical that mCaptcha would actually work besides perhaps temporarily slowing bots down due to being niche. How expensive can you make it without hurting legitimate users? And how expensive does it need to be to discourage bots? Especially when purposefully designed bots can actually do the kinda math we're talking about in optimized software and hardware while legitimate users can't.

[–] [email protected] 16 points 1 year ago (1 children)

Hard agree.. currently of the top 20 fastest growing servers in the fediverse most are instances with less than 10 active users but they are showing 50k - 70k bot accounts.

[–] [email protected] 3 points 1 year ago (1 children)

What? Can’t they get defederated if it’s this obvious?

[–] [email protected] 1 points 1 year ago

You can find them in "Top 20 Fastest Growing Servers" on here https://fedidb.org/

and instances can add them to their blacklist. though it probably helpful to reach out to the admins. many are new and are unaware of how it works.

[–] [email protected] 15 points 1 year ago* (last edited 1 year ago) (2 children)

Bot registrations can also be slowed down by just ... slowing down.

Real users don't need a registration to happen within 250 milliseconds. It's okay to delay it for several seconds just to rate-limit bots.

(This is sometimes described as the "tarpit" approach.)

[–] [email protected] 11 points 1 year ago (2 children)

Yes, but the point is that and captchas are not exclusive. I hope devs will backtrack on their intention to remove captchas and instead make them a default.

[–] [email protected] 5 points 1 year ago

Yep. Successful anti-spam usually relies on a mix of different techniques, not just one!

[–] [email protected] 3 points 1 year ago

I think the commenter you replied tonwas giving an additional suggestion rather than an alternative to your original suggestion

[–] [email protected] 4 points 1 year ago (1 children)

If you add a big delay the botters will just run more requests in parallel. It is a tiny barrier but in a completely different league than even a simple captcha.

[–] [email protected] 4 points 1 year ago (1 children)

@kevincox @fubo I've tried actually shunting the bots into a queue that basically sets the TCP receive window to 1. You're quite correct, the bots just spawn off more processes.

[–] [email protected] 2 points 1 year ago

And then you respond by limiting access by IP. That degrades the experience a bit for large networks like universities, but if it's limited to logins and signups, it can be acceptable.

And then they respond with bot nets, and then you know you've hit the mainstream.

[–] [email protected] 8 points 1 year ago

I'd say setting registrations to closed and having the operator enable/configure which to use is the best default. CAPTCHAs can also be automated, so this won't stop anyone that is ambitious enough. If someone sees value in automating account registrations, they might be willing to pay for the CAPTCHAs to be solved for fraction of a US cent each.

[–] [email protected] 8 points 1 year ago (1 children)

Agreed, I'm really concerned about the fact that email verification and captchas are available but off by default. With the state of the internet now they really should be on by default.

[–] [email protected] 2 points 1 year ago (1 children)

Arguing against captchas like this is a prime example of letting perfect be the enemy of good.

[–] [email protected] 1 points 1 year ago* (last edited 1 year ago)

those people probably leave their doors open because even the strongest lock can be broken anyway